“Seiza” is a Japanese traditional way of sitting which has been around since the Edo Period (17th century), and involves kneeling so that ones knees touch the floor, with feet are folded underneath, resting roughly below the spine. See this page for a picture of people sitting in a group in seiza. There are different variations in how much space you put between your knees, but it is important to make sure your back is roughly straight and avoid slouching forward.

It is interesting to note that this type of sitting is written in modern Japanese as 正座, which is made from the characters for “correct” and “sit”, which together mean something like “correct way to sit”. Originally, it was used as a posture to worship Shinto Gods or Buddha, and also for when prostrating oneself before a Shogun.

In modern Japan, some people still sit in seiza in their homes (either on tatami mats, carpet, or zabuton (square pillows)). However, now that western-style houses are becoming more popular, the practice of sitting in seiza has decreased and is less common in daily life. It is still frequently used in the Japanese Tea Ceremony, Traditional Dance, Funerals, and some martial arts including Kendo, Aikido, and Iaido.

If you haven’t before, I recommend trying this unique way of sitting yourself. If you do, avoid using a hard floor and try it just for a minute or two at first, because your legs are likely to get numb after some time. Numbness isn’t just for those new to the posture, it happens to some Japanese people as well who are used to sitting this way. In fact, in some schools this way of sitting is utilized as a form of punishment.

Another drawback of this posture is that it puts pressure on the knees and legs, and it is recommended by doctors to avoid seiza for those who have certain physical conditions. Because of this and the numbness, I have seen people take a break from seiza to sit in indian style, and I imagine that is especially permitted for older people who have week knees.

Ironically, I sit in seiza frequently because it seems to take pressure off my back and avoids back pain which creeps in if I sit in other postures. I think this is because keeping the back straight in this position is more natural, whereas with crossed legs the back doesn’t have much support. I do it not only in my living room during meals, but even at work in a normal chair (after taking off my shoes). I usually shift positions every few minutes to avoid numbness or pain in my legs.